<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style type="text/css">
      * {
        margin: 0;
        padding: 0;
      }
      body,
      html {
        width: 100%;
      }
      nav {
        /*calc()可以传两个参数  % - px其他像素值  自适应的写法
             赋值运算符 前后 记得要给它加上空格
             */
        width: calc(100% - 60px);
        height: 35px;
        line-height: 35px;
        color: white;
        padding: 0 30px;
        background-color: #2dbb55;
      }
      ul {
        list-style: none;
      }
      ul > li {
        float: left;
        margin-right: 10px;
        cursor: pointer;
        position: relative;
        padding: 0 20px;
      }
      ol {
        position: absolute;
        width: 100px;
        left: 0px;
        display: none;
      }
      ol > li {
        background-color: #11a13a;
        height: 30px;
        line-height: 30px;
        font-size: 13px;
        text-align: center;
      }
      .li_active {
        background-color: #11a13a;
      }
    </style>
  </head>
  <body></body>
</html>
